1. Field
The present disclosure relates to self-humidifying Proton Exchange Membrane Fuel Cell (PEMFC) and in particular, to the design, preparation and properties of proton-conducting composite membrane confined in a zeolite, zeotype and/or molecular sieve-coated porous substrate.
2. Background
The perfluorosulphonic acid (PFSA) polymer such as Nafion from DuPont® is the most common polymer electrolyte membrane used in a Proton Exchange Membrane Fuel Cell (PEMFC) due to its high proton conductivity and excellent long-term stability under a fully hydrated condition. (Nafion is a registered trademark of E.I. duPont de Nemours.) The PFSA polymer loses mechanical and dimensional stabilities at high temperature due to its low glass transition temperature, which restricts the operating temperature of PEMFC below 80° C. The low operating temperature brings many problems including greater sensitivity to fuel impurities (e.g., CO, H2S) and complicated heat and water management. The proton conductivity of PFSA polymer also suffers a sharp drop under low membrane hydration, resulting in poor performance. Therefore, external humidification equipment is often necessary when using PFSA polymer, which complicates the system design and operation, and lowers the overall energy efficiency.
Many attempts have been made to achieve operation without humidification, including:                new membrane structure design        new proton conductor operated under low humidity and high temperature        self-humidifying electrolyte membrane based on PFSA polymer, e.g., zeolite-Nafion composite membrane.        